This project is aimed at studying the functional alterations in the microvasculature of animals under the condition of experimental diabetes mellitus. We have observed that the permeability of peritubular capillaries in the renal cortex to albumin increases, when the animals are rendered diabetic and no insulin replacement is provided; the specific method for carrying out these measurements has been worked out in our laboratory. During the forthcoming period of this research, activity will be aimed at determining (1) whether the developemnt of microvascular alteration can be delayed or accelerated, (2) if any circulation bed not as yet studied in the diabetic animal especially vulnerable to diabetic vascular disease.